Spinodal decomposition, nuclear fog and two characteristic volumes in thermal multifragmentation

Thermal multifragmentation of hot nuclei is interpreted as the nuclear liquid-fog phase transition inside the spinodal region. The experimental data for p(8.1GeV) + Au collisions are analyzed within the framework of the statistical multifragmentation model (SMM) for the events with emission of at least two IMFs. It is found that the partition of hot nuclei is specified after expansion to a volume equal to Vt = (2.6+-0.3) Vo, with Vo as the volume at normal density. However, the freeze-out volume is found to be twice as large: Vf = (5+-1) Vo.Comment: 8 pages, 6 figures, to be published in Nucl.Phys.

Nuclear multifragmentation and fission: similarity and differences

Thermal multifragmentation of hot nuclei is interpreted as the nuclear liquid--fog phase transition deep inside the spinodal region. The experimental data for p(8.1GeV) + Au collisions are analyzed. It is concluded that the decay process of hot nuclei is characterized by two size parameters: transition state and freeze-out volumes. The similarity between dynamics of fragmentation and ordinary fission is discussed. The IMF emission time is related to the mean rupture time at the multi-scission point, which corresponds to the kinetic freeze-out configuration.Comment: 7 pages, 3 Postscript figures, Proceedings of IWM 2005, Catani

Spin-polarized states of matter on the surface of a three-dimensional topological insulator with implanted magnetic atoms

We describe the occurrence of a spin-polarized ferromagnetic state on the surface of a topological insulator with implanted 3d transition-metal atoms, within a model which takes into account the hybridization between the (s, p) orbitals of the insulator and the d orbitals of the metal, entailing the delocalized character of magnetic moments. Depending on the position of the Fermi level, the energy spectrum of this state displays both metallic and semimetallic, or semiconducting characteristics

Spin ordering in semiconductor heterostructures with ferromagnetic delta layers

We report on theoretical study of the magnetic properties of a magnetic metal delta layer embedded into a nonmagnetic nondegenerated semiconductor, taking into account the diffusion smearing, that is unavoidable in the case of delta doping. The system of interest is modeled by the delta layer core, enriched in metal atoms, and a nearly depleted smeared periphery. Confinement states in the form of two-dimensional spin-polarized subbands within the semiconductor band gap arise from potential and exchange scattering of carriers at the core. The mechanism of indirect exchange between impurity spins placed within the peripheral region of the delta layer, via partially occupied confinement states, is analyzed. It is shown that, in the case of a ferromagnetic core, the impurity spins align parallel or antiparallel to the core magnetization, due to the polarization of carriers in the confinement states. Allowing for the confinement mechanism of interaction between the impurity spins as well as for the exchange mechanism through deep levels of the semiconductor host, the magnetic configuration of the impurity spins in the peripheral region of the delta layer is obtained in the framework of a phenomenological approach